Airpods fail to update firmware to 9A348 from the beta firmware

Did you already report this potential software issue directly to Apple Techs by using the Feedback link?

Feedback - AirPods - Apple

Did you also try to reset your AirPodsPro3 and try to update the firmware again, as explained in this article?

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1. Make sure that your iPhone, iPad, or Mac is updated to the latest version of iOS, iPadOS, or macOS, and that Bluetooth is on.
2. Make sure that your AirPods are connected via Bluetooth to your iPhone, iPad, or Mac.
3. Connect your iPhone, iPad, or Mac to Wi-Fi.
4. Connect your charging case to power.
5. Put your AirPods in their charging case and close the lid. Keep the lid of the charging case closed, and keep your AirPods in Bluetooth range of your iPhone, iPad, or Mac.
6. Wait at least 30 minutes for the firmware to update.
7. Open the lid of the charging case to reconnect your AirPods to your iPhone, iPad, or Mac.
8. Check the firmware version again.

If you still can’t update your firmware, reset your AirPods, then try to update your firmware again.

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copied from: About firmware updates for AirPods - Apple Support

Have a look at this answer from the Beta FAQ's page:

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The iOS, iPadOS and macOS betas come with the built-in Feedback Assistant app, which can be opened from the Home screen on your iPhone or iPad or from the Dock on your Mac. The Feedback Assistant app is also available from the help menu of any app by selecting Send Feedback. If you’re running the tvOS, HomePod software, watchOS beta or AirPods beta, you can submit feedback through the Feedback Assistant app on an enrolled iPhone, iPad or Mac. When you experience an issue or something does not work as expected, send your feedback directly to Apple with Feedback Assistant.

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copied from: FAQ - Apple Beta

I have submitted feedback via the link u provided. Is there an app for providing feedback in the future on the stable iOS versions or do i have to use the web form?